Subsurface engraving of three-dimensional sculpture

ABSTRACT

A matrix is formed into a desired shape by pouring transparent liquid material into a mold. The material progresses from the liquid to the gelatinous state. Laser sculpting steps are performed when the material is still in a gelatinous condition to form small spots in the matrix. Because the material is non-solid gel when the laser beam applies its focused energy, there is no cracking or destruction. Intensity and duration of the laser pulse determine the size of the spots as does the timing in relation to the matrix material finally changing from gel to solid. Particular visual effects are produced at different degrees of solidity when sculpting. The liquid in the mold may be pressurized for removal of air bubbles after initial pouring of the matrix material and application of pressure after the laser sculpting controls the size of the spots in the finished product.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a division of U.S. application Ser. No. 09/645,124 filed Aug.24, 2000, now U.S. Pat. No. 6,537,479.

BACKGROUND OF THE INVENTION

This invention relates to the creation of a sculpture generated by alaser beam directed at a transparent matrix, and more particularly, to asculpture engraved within the surfaces of a transparent matrix.

There are many souvenirs and art objects wherein a translucentghost-like image in two or three dimensions is seen floating within asolid piece of clear plastic or glass.

In recent years these translucent objects have been produced internallyusing a programmed laser that is brought to focus sequentially at manylocations within the transparent matrix. The energy concentrated at thepoint of focus changes the matrix material so that the translucentthree-dimensional object is created of many spots within the transparentplastic or glass matrix.

XYZ axis programming in positioning the matrix relative to the lasersource provides enough spots (dots) within the matrix to define adesired image. Size of the spots can be controlled by controlling theenergy and duration of the laser beam, and the size of the internalsculpture can be varied by setting the controls on the computer program.

The concentrated laser beam forms tiny cracks, that is, a destruction,in the matrix material at the point of beam focus and this cracking orother destruction provides the translucent regions which taken togethercreate the sculpted shape. The amount of cracking or other distortionwithin the matrix is determined by the intensity and duration and typeof the laser beam. In U.S. Pat. No. 5,575,936, the action of the laserbeam is described as “local destruction” or “local disruption”. In U.S.Pat. No. 5,886,318, the inventor describes a laser spot with a powerdensity exceeding ten times the destruction threshold of the glassobject under processing. At column 1, U.S. Pat. No. 5,637,244 speaks of“macro-destructions”. In the '244 invention, the techniques wereimproved to provide “microdestructions” adjustable in size. Clearly inthe prior art, there is a degree of cracking/destruction at the point ofconcentration of the laser beam.

However, a problem arises when the laser spots/dots/cracks/destructions,etc. are too close together or too near the external surfaces of thematrix. Then, a defect in the internal sculpture results or subsequentchanges with time may render the sculpture valueless. This internaldamaging of the material limits the closeness of the dots that aregenerally formed in the prior art as well as their location relative tothe outer surfaces of the matrix. The quality of the internal sculptureis adversely affected.

What is needed is a method of producing subsurface three dimensionalsculpture by laser engraving that does not crack or destroy the matrixmaterial in order to form the sculpture, thereby permitting a finersculpture with closer “dots” and an ability to locate the internalsculpture at or near external surfaces of the matrix without laterchanges or interactions.

SUMMARY OF THE INVENTION

In accordance with the invention an improved sculpturing procedureresults in an improved product. In such subsurface sculpting, clearmaterials, whether glass or plastic, are generally used as the matrixmaterials. These matrix materials may be in three states, namely,liquid, gelatinous, and solid. In the prior art, the laser sculpting hasbeen done in solid material. The matrix is formed into the desired shapeby pouring liquid material into a mold that has been prepared, forexample, in special instances, by an artist. With time, the materialprogresses from the liquid state to the gelatinous state and finally tothe solid state. Thereafter, laser sculpting commences in the knownmanner.

In accordance with the present invention, the laser sculpting steps areperformed when the matrix material is still in a gelatinous condition.As a result, small spots, dots or bubbles are formed, which are tiny,and because the material is a non-solid gel when the laser beam appliesits focused energy, there is no cracking or destruction. What the actualprocess in formation of the spots/dots/bubbles is, is not preciselyknown. It is not known whether the matrix material locally evaporates,for example, or perhaps the dots/bubbles are the result of some chemicalprocess that occurs by the application of high intensity thermal energy.However, it has been found possible to link dot to dot and even drawcontinuous lines with the laser beam. This is not possible in the priorart where the material is cracked/destroyed, as the thermal energy isapplied to a solid. Intensity and duration of the laser pulse in thepresent invention determine the size of the dots/bubbles that areproduced as does the timing in relation to the matrix material finallychanging from gel to solid. All of the possible conditions between theliquid state and the solid state for the matrix material have not yetbeen explored in actual sculpting. Particular visual effects can beexpected at different degrees of solidity when sculpting.

Thus, there is a wide range of control of the internal sculpture that isproduced. Additionally, sculpting can be performed on the externalsurfaces of the matrix as well as close to these external surfaceswithout cracking/destruction. Spacing between dots and lines allow forthe production of a three-dimensional-translucent, see-throughsculpture, floating ghost-like in a clear matrix. The matrix materialmay be colorless or tinted so long as it remains sufficiently clear topermit the laser beam penetration from its external position.

The liquid in the mold may be pressurized for removal of air bubblesafter initial pouring of the matrix material into the mold, andapplication of pressure on an exposed surface of the matrix after thelaser sculpting can be used to control the size of the dots/bubbles thatresult in the finished product.

Because the sculpting is performed on a matrix in a semi-solid, that is,somewhat gelatinous state, there is no cracking of the matrix material,and a finer detailing of the finished sculpture is possible.

Accordingly, it is an object of the invention to provide an improvedmethod for subsurface engraving of a three-dimensional sculpture withina transparent matrix.

Another object of the invention is to provide an improved method forsubsurface engraving three-dimensional sculpture within a transparentmatrix wherein dots/bubbles may be joined one to the other, or in acontinuous line.

Yet another object of the invention is to provide an improved subsurfaceengraving of a three-dimensional sculpture in a transparent matrixwherein the sculpture is both on the surface of the matrix and withinthe matrix.

Still another object of the invention is to provide an improvedsubsurface engraving of a three-dimensional sculpture within atransparent matrix, wherein the sculpture is close to an externalsurface of the matrix.

The invention accordingly comprises the several steps and the relationof one or more of such steps with respect to each of the others, and thearticle possessing the features, properties and the relation ofelements, which are exemplified in the following detailed disclosure,and the scope of the invention will be indicated in the claims.

Still other objects and advantages of the invention will be apparentfrom the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

For a full understanding of the invention, reference is had to thefollowing description taken in connection with the accompanyingdrawings, in which:

FIG. 1 is a three-dimensional sculpture engraved in a solid matrix ofacrylic by a focused laser beam in accordance with the prior art;

FIG. 2 is similar to FIG. 1 illustrating a prior art engraving of asculpture in a solid glass matrix;

FIG. 3 is a three-dimensional sculpture in accordance with the inventionthat was engraved by a laser beam while the matrix material was in agelatinous state;

FIG. 4 is a schematic diagram illustrating an apparatus for a knowntechnique of three-dimensional sculpturing within a solid transparentmatrix;

FIG. 5 is a side elevation of an object comprising a subsurfacehemispheric engraving that extends to an external surface of thetransparent matrix; and

FIG. 6 is an exemplary rectangular mold for use in the method inaccordance with the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 4, taken from U.S. Pat. No. 5,575,936, mentioned above andincorporated herein by reference, illustrates a basic method ofsubsurface engraving in a solid transparent matrix. Fractures areproduced in the matrix 15 by a laser beam 12 that is focused within thematrix 15 by a lens 13. The solid matrix 15 is positioned on a movableplatform 16 which is moved under direction of the controller 17. Thusthe laser 11 can produce a plurality of destructions/disruptions at thefocal point 14 which is moved within the matrix 15 from dot to dot.

Refinements in this procedure are added in the other patents mentionedabove, which are also incorporated herein by reference. The laser may bepulsed or operate steady state while the focal point location is changedto produce a plurality of dots. Procedures for operation of the laserapparatus itself and its control are not a novel portion of the presentinvention and accordingly, are not discussed in detail herein.

In the present invention, a design mold (FIG. 6) is provided having oneor more flat transparent windows through which an externally locatedlaser beam can be directed into the cavity of the design mold. Thedesign mold 20 may be, for example, a simple structure similar to a fishtank or it may be, for example, of a design created by an artist suchthat the matrix which is produced is in itself an object of art, thatis, a sculpture. The design mold has an opening at the top, which allowsventing and filling with matrix material.

The matrix material is poured into the mold to fill the mold to thedesired level. The material is poured slowly so as to avoid entrapmentof tiny air bubbles in the matrix material. The matrix material may be asingle component or may contain two or more components in a mixture.Materials used for this matrix's include transparent acrylic resin,polyester resin, polyurethane, and glass. Each of these is athree-staged material which can be mixed and poured into the mold andwill go from a liquid state to a gelatinous state and finally to a solidstate with the passage of time and/or application of heat.

It should be noted that if, in pouring the liquid matrix material intothe mold, air bubbles are formed, then the entire mold may be placedinto an autoclave for a few minutes to remove the bubbles by applicationof pressure, for example, up to approximately 125 PSIG. This causes thebubbles to rapidly rise to the surface and escape. Then the mold withbubble-free matrix material in the liquid state is removed from theautoclave. This bubble removal must generally be completed before thematrix material begins to gel.

After a specific period of time, the liquid matrix materials pouredinside the mold begin to enter the second physical stage, that is, theliquid begins to gel. At a selected time, the entire mold, together withthe gelling mixture is placed on the engraving machine, for example, asillustrated in FIG. 4 and as described in the above mentioned patents.The desired sculpture is created by passage of the controlled laser beamthrough the flat transparent windows provided in the mold. The beamfocuses in the gel matrix to produce the desired lines and dots. Inaccordance with the present method of engraving in gelatinous materials,dots/bubbles are formed without destruction/cracking of the matrixmaterial.

After the sculpting is completed, the mold together with sculpturedmatrix are removed from the laser apparatus and left to further cure andharden toward the solid state.

On the other hand, after the sculpting is complete, the mold with thesculpting material can again be placed into the autoclave where pressuremay be applied and the temperature may be increased for fast curing.Application of pressure controls the size of the bubble created by theengraving process. Increasing the pressure reduces the size of thedots/bubbles.

After the sculptured matrix material has sufficiently solidified themold is removed. The final product may be slightly resilient or rigid.For original or expensive items created by a well-known artist, theartist may want to specially finish the external surfaces of the artobject which has been created. On the other hand, lower cost souvenirobjects may be simple shapes made in simple molds.

During the process of subsurface engraving, because the engraving isdone while the matrix material is in a gelatinous state, the laser beamcreates a tiny bubble, which nevertheless may be specified as small,medium or large from a production viewpoint, while still actually“tiny”. This size is controlled based upon the power and time ofapplication of the focused laser beam. The matrix material is notdamaged in the present procedure by tiny cracks or destructions as areproduced on a hard material such as when engraving solid glass orplastic. A continuous line will be drawn by a dot to dot attachment ofdots/bubbles or a continuous line can be generated with the presentinvention by continuous relative motion between the matrix material andfocal point of the laser beam without fear that the material will crack.

Two and three-dimensional subsurface engravings have been formed using aRSY OSC diode pump Nd-Yag diode engraver, manufactured by Rofin-SinarLaser Corporation, and controlled by VitroCam computer aide software,which are commercially available.

The matrix material need not be colorless but must be transparent to thelaser beam when in a semi-solid gelatinous state. The present methodproduces a finer product and allows an artist to control the quality andintensity of the created image. For the first time, the gelatinous stateof the material permits use of the subsurface engraver to create acontinuous drawing image by either a dot by dot technique or bycontinuous lines. The gelatinous state of material allows sculpting oflarger images within a matrix and closer to the exterior of the mold,without cracking or damaging the matrix material.

Because of the gelatinous state of the matrix material, it is possibleto produce a sculptured image beginning outside at the matrix surfaceand continuing to the inside of the matrix without damaging the piece(FIG. 5). FIG. 5 illustrates a hemisphere 22 sculpted in dots. Thehemisphere is visible from every face of the object and may be made toappear, for example, solid, or hollow like a tennis ball that is slicedin half, depending on the program that controls the laser beam.

It should be understood that whereas the method described above beginswith filling a mold with liquid matrix material, it is also possible topractice the method by beginning with a solid matrix which is heateduntil the matrix material enters a gelatinous state. Then, the gelledmatrix may be sculptured as described above. Following sculpturing thematrix material is allowed to harden. The final product may be slightlyresilient or rigid. This alternative procedure is only effective on athermoplastic plastic matrix, and may also be used with glass.

As illustrated in FIGS. 1-3, the difference in quality between thesculptures produced by the present method (FIG. 3) and the destructiveprior art techniques is noticeable in the finished product.

It should also be understood that the method, in accordance with theinvention, can be used to produce objects that are not limited to thoseof ornamental value. For example, the techniques in accordance with theinvention can be used to form reticles, and be used in photographic lenssystems, gunsights, instruments including optical systems, and the like.The engraving may be on one or both of internal and external surfaces ofthe object.

The molds can be made with windows of any suitable transparent materialincluding silicones. The matrix material may be tinted so long as itremains transparent to the externally applied laser beam that is focusedwithin the matrix material.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained and,since certain changes may be made in carrying out the above method andin the article set forth without departing from the spirit and scope ofthe invention, it is intended that all matter contained in the abovedescription and shown in the accompanying drawings shall be interpretedas illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

What is claimed is:
 1. An object having an engraved subsurface image,comprising: (a) a matrix material that is transparent to a laser beam,said matrix material being in a physical gel state that is between arigid state and a flowable state; (b) at least one modified portionproduced in said matrix material by a laser beam directed towards saidmatrix material at a point of focus of said laser beam; (c) said atleast one modified portion being visible and appearing as a bubble fromoutside said matrix material, and (d) said at least one modified portionbeing generated without destruction or cracking of said matrix material.2. An object in accordance with claim 1, wherein said transparent matrixmaterial is one of colorless and tinted.
 3. An object in accordance withclaim 1, wherein said at least one modified portion remains in saidmatrix material upon the hardening of said matrix material from a gelstate to a hardened state.
 4. An object in accordance with claim 3,wherein said matrix material is initially provided in a rigid state andis changed to said physical gel state by heating of said matrixmaterial.
 5. An object in accordance with claim 1, wherein said matrixmaterial is one of glass and a thermoplastic material.
 6. An object inaccordance with claim 1, further comprising a plurality of modifiedportions produced by said laser beam, said point of focus being movedrelative to said matrix material in accordance with a controlledcomputer program, whereby an engraving of said matrix material in two orthree dimensions is made visible when looking at said matrix materialfrom its exterior.
 7. An object in accordance with claim 1, wherein saidat least one modified portion is formed in said matrix material byfocused thermal energy of said laser beam.
 8. An object in accordancewith claim 6, wherein said modified portions being respectively at leastone of (a) connected dot to dot to other said modified portions, (b) ina continuous line, and (c) separate and individual dots.
 9. An object inaccordance with claim 6, wherein said engraving is formed on and extendsfrom an outer surface of said matrix material into an interior volume ofsaid matrix material.
 10. An object in accordance with claim 3, whereinthe size of said at least one modified portion is varied by pressurizingsaid matrix material prior to the hardening of said matrix material fromsaid physical gel state to said hardened state.
 11. An object having anengraved subsurface image, comprising: (a) a mold having a portion thatis transparent to a laser beam; (b) a matrix material provided in saidmold, said matrix material being transparent to a laser beam, saidmatrix material being initially in a physical gel state that is betweena rigid state and a flowable state; (c) at least one modified portionproduced in said matrix material by a laser beam directed towards saidmatrix material at a point of focus of said laser beam while said matrixmaterial is in said physical gel state; wherein said matrix materialhardens into a rigid state following formation of a midified portion;(d) said at least one modified portion being visible and appearing as abubble from outside said matrix material when said matrix material is inboth said physical gel and rigid states, and (e) said at least onemodified portion being generated without destruction or cracking of saidmatrix material when said matrix material is in both said physical geland rigid states.
 12. A system for subsurface engraving comprising: (a)a matrix material that is transparent to a laser beam, said matrixmaterial being in a physical gel state that is between a rigid state anda flowable state; (b) means for producing at least one modified portionwithin said matrix material without destruction or cracking of saidmatrix material, and (c) said at least one modified portion beingvisible and appearing as a bubble from outside said matrix material, (d)wherein said means further comprises subjecting said matrix material insaid gel state to a laser beam directed towards said matrix material toproduce at least one modified portion within said matrix material at apoint of focus of said laser beam.
 13. The system in accordance withclaim 12, further comprising control means for producing a plurality ofmodified portions produced by said laser beam, wherein said controlmeans moves said point of focus of said laser beam relative to saidmatrix material, whereby an engraving of said matrix material in two orthree dimensions is made visible when looking at said matrix materialfrom its exterior.